Method of thermal deburring of metal parts

ABSTRACT

A method of thermal deburring of metal parts which is carried out in a chamber in two stages. The chamber is initially filled with a mixture of a combustible gas and air, the amount of each component in the mixture and the pressure thereof being dependent on the necessity to ensure the burning-out of oils and evaporation of moisture from the surface of parts being treated. The mixture is subsequently ignited. As a result, the moisture evaporates, and the oils burn out. Products of combustion are then expelled from the chamber. Then the chamber is filled with a mixture of a combustible gas and oxygen and the mixture is ignited, and the burrs on the parts are burnt down.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to methods of deburring of parts, and morespecifically, to methods of thermal deburring of metal parts.

2. Description of the Prior Art

Known in the art is a method of thermal deburring of metal parts,wherein the parts being treated are placed in a chamber, the latter isfilled with a mixture of a combustible gas and oxygen, the amount ofeach component in the mixture and its pressure being dependent on thematerial and dimensions of parts being treated, and the mixture issubsequently ignited (cf. U.S. Pat. No. 3,475,229, class 148-9,published Oct. 28, 1969; USSR Inventor's Certificate No. 615,094, classB23K 28/00, published July 25, 1978).

Using the above method, it is necessary to perform an additionaloperation to degrease and remove moisture from the surface of the partsbeing treated prior to placing them in the chamber. This operation hasbeen necessitated by the fact that oils on the surface of parts combinedwith oxygen are conducive to uncontrollable combustion of thecombustible gas and oxygen in the chamber, which interferes with theprocess of treatment.

Moisture on the surface being treated results in a drastic increase inthe energy required to remove the burrs, because part of the energy isspent on evaporation. As to the operation to degrease and dry thesurface of parts, it is rather labour-consuming and toxic. Moreover, theoperation in question calls for a separate workplace provided withrelevant machinery.

SUMMARY OF THE INVENTION

The present invention is aimed at providing a method of thermaldeburring of metal parts according to which parts in a chamber aretreated in such a way that it is possible to eliminate labour consumingand toxic operations of degreasing and drying surfaces of parts beingtreated and uncontrollable ignition in the chamber of mixture of acombustible gas and oxygen.

The invention substantially resides in a method of thermal deburring ofmetal parts, wherein the parts being treated are placed in a chamber,the latter is filled with a mixture of a combustible gas and oxygen, theamount of each component in the mixture and the pressure thereof beingdependent on the material and dimensions of parts being treated, and themixture is ignited according to the invention, which presupposes thatprior to being filled with a mixture of a combustible gas and oxygen thechamber is filled with a mixture of a combustible gas and air, theamount of each component and the pressure of the latter mixture beingdependent on the necessity to ensure the burning-out of oils andevaporation of moisture from the surface of parts being treated, themixture is ignited to expel oils and moisture from the surface of parts,and the products of combustion are subsequently removed.

The proposed method of thermal deburring of metal parts allows labourconditions to be improved, the quantity of additional equipment to bereduced, and interference with the parts treatment process to beavoided.

BRIEF DESCRIPTION OF THE DRAWINGS

Further the present invention will become more fully apparent withreference to specific embodiments thereof taken in conjunction with theaccompanying drawings, wherein:

FIG. 1 illustrates a chamber for thermal deburring of metal parts toimplement a method for thermal deburring of metal parts, according tothe invention (longitudinal section); and

FIG. 2 is a diagram of the variations of the pressure in the chamber,depending on the time, and explaining the method, according to theinvention with time t in seconds being plotted on the abscissa andpressure P in MPa, o n the ordinate.

DESCRIPTION OF THE BEST MODE FOR CARRYING OUT THE INVENTION

The method of thermal deburring of metal parts, according to theinvention, consists in that a part 1 being treated with burrs 2 thereonis placed onto a bottom 3 of a chamber 4. The latter is then filled witha mixture of a combustible gas and air (time interval t₁ in FIG. 2), theamount of each component in the mixture and the pressure thereof beingdependent on the necessity to ensure the burning-out of oils andevaporation of moisture from the surface of the part 1 being treated(FIG. 1). The mixture is fed into the chamber 4 through an inlet valve5. Said mixture is ignited in the chamber 4 with the aid of an ignitionplug 6 to expel oils and moisture from the surface of the part 1 (timeinterval t₂ in FIG. 2), and the combustion products are removed throughan outlet valve 7 (time interval t₃ in FIG. 2). The chamber 4 issubsequently blown through with air (time interval t₄ in FIG. 2).Following this, the chamber 4 is filled with a mixture of a combustiblegas and oxygen through the valve 5 (time interval t₅ in FIG. 2), theamount of each component in the latter mixture and the pressure thereofbeing dependent on the material and dimensions of the part 1 beingtreated. The mixture is then ignited by means of the ignition plug 6.The high temperature and pressure resulting from the combustion of thegas-oxygen mixture (time interval t₆ in FIG. 2) remove the burrs 2 fromthe part 1. The processed combustion products are discharged into theatmosphere through the valve 7 (time interval t₇ in FIG. 2), and thetreated part 1 is taken out of the chamber 4.

The table below shows specific examples of the method, according to theinvention.

                  TABLE                                                           ______________________________________                                        Material of                                                                   part being Content of elements in mass percent                                Nos  treated   C      Si  Mn   Fe     Cu  Zn  Al                              ______________________________________                                        1    Steel     0.45   0.2 0.6  balance                                                                              --  --  --                              2    Brass     --     --  --   --     60  40  --                              3    Aluminium --     5.0 0.3  1.2    2.5 0.3 balance                              alloy                                                                    ______________________________________                                                                   Mixture of com-                                                 Mixture of com-                                                                             bustible gas                                                    bustible gas and air,                                                                       and oxygen,                                        Dimensions,  pressure in MPs                                                                             pressure in MPa                                    Nos  mm          CH.sub.4 air    CH.sub.4                                                                             O.sub.2                               ______________________________________                                        1    50 × 50 × 100                                                                 0.04-0.08                                                                              0.4-0.8                                                                              0.25-0.10                                                                            0.8-3.0                               2    50 × 50 × 100                                                                 0.04-0.06                                                                              0.4-0.6                                                                              0.25-0.50                                                                            0.8-1.5                               3    50 × 50 × 100                                                                 0.02-0.04                                                                              0.2-0.4                                                                              0.15-0.30                                                                            0.5-1.0                               ______________________________________                                    

The method of thermal deburring of metal parts, according to theinvention, ensures a high quality of deburring, obviates the necessityfor performing additional labour-consuming and toxic operations todegrease the surface of parts and remove moisture therefrom, and makesit possible to attain the stability of the deburring process bypreventig uncontrollable self-ignition of a mixture of a combustible gasand oxygen in the chamber.

The invention may be used to advantage at machine-building enterprisesto deburr metal parts.

We claim:
 1. A method of thermal deburring of metal parts, comprisingthe steps of placing the parts being treated into a chamber; filling thechamber with a mixture of a combustible gas and air, the amount of eachcomponent and the pressure of the latter mixture being dependent on thenecessity to insure the burig-out of oils and evaporation of moisturefrom the surface of the parts being treated; igniting the gas and airmixture to expel oils and moisture from the surface of parts; removingthe products of combustion; filling the chamber with a mixture of acombustible gas and oxygen, the amount of each component of the mixtureand the pressure thereof being dependent on the material and thedimensions of parts being treated; and igniting the gas and oxygenmixture to effect deburring.